The plan of this research proposal is to identify the populations of lymphocytes participation in cellular and humoral immune response to the basic protein (BP) of myelin and to ascertain their roles in mediating clinical and histological signs of experimental autoimmune encephalomyelitis (EAE). Subpopulations of normal T-lymphocytes, separated on the basis of buoyant density, will be assayed in vitro for mitogen responsiveness and in vivo, in neonatally thymectomized (NTX) recipient rats, separately and in combination with other T-cells, for their immune responsiveness to BP. X-irradiation and specific anti-B- lymphocyte sera will also be used in investigating whether antibody has a role in effecting clinical signs of EAE.